"Homoallyl Interaction between the Nitrogen Lone Pair and the Non-adjacent π-Bond. 1H and 13C Nuclear Magnetic Resonance Contact Shifts and the Orientation of the Lone Pair Electrons in 2-Azabicyclo[2.2.2]oct-5-enes"Isao Morishima and Kenichi Yoshikawa, The Journal of the American Chemical Society, 97(11), 2950–2956 (1975)

"Photoelectron Spectroscopic Study of Cyclic Amines. The Relation between Ionization Potentials, Basicities, and s Character of the Nitrogen Lone Pair Electrons"Kenichi Yoshikawa, Mikio Hashimoto and Isao Morishima, The Journal of the American Chemical Society, 96(1), 288–289 (1974)